可以
解析:
sinx-cosx
=1●sinx+(-1)●cosx
a=1,b=-1
√(a²+b²)=√2
φ=arctan(b/a)=arctan(-1)=-π/4
故,
sinx-cosx
=√(a²+b²)sin[x+arctan(b/a)]
=√2sin(x-π/4
y=sinx+(√3)cosx用辅助角公式怎么求值域?
解:y=2[(1/2)sinx+(√3/2)cosx]=2[sinxcos(π/3)+cosxsin(π/3)]=2sin(x+π/3)
由于-1≦sin(x+π/3)≦1,故-2≦2sin(x+π/3)≦2,即值域为[-2,2]。